Multiplex electrical pulse communication system



D. D. 'GRIEG 2,498,678

MULTIPLEX ELECTRICAL PULSE COMMUNICATION SYSTEM 13 Sheets-Sheet lTfifl/VSM/TTE/P m illlillwwVilfili m m T M fl "I" m a 5 5 M M@ Z W M m I2/ 2f 0 W u M iii}? I W a M R m m a 7% F a L m M u w m P w u E I T. P 7G w 5 6 0 mm N a p f l A 2 2 ya PK 0 m fi W llllllllllll 8 N "N 2 K. f mR m R R n m M Z, w M W 1 I r m a 0 2 k R L v z k w m a 4/ (w 1n 4 m m mE N g c m 4 a 5 d a m a m M m M M w a a 6 Feb. 28, 1950 Filed Sept. 29,1945 Feb. 28, 1950 D. D. GRIEG 2,498,678

MULTIPLEX ELECTRICAL PULSE COMMUNICATION SYSTEM Filed Sept. 29, 1945 l3Sheets-Sheet 2 CWA/V/VEL CH/l/V/VEL a CW/l/V/VEA 6 M/XER ATTORNEY D. D.GRIEG 2,498,678

MULTIPLEX ELECTRICAL PULSE COMMUNICATION SYSTEM Feb. 28, 1950 13Sheets-Sheet 5 Filed Sept. 29, 1945 7 ATTORNEY Feb. 28, 1950 13Sheets-Sheet 5 Filed Sept. 29, 1945 flu-f1 1 #2. 3 W m M 1 w W mmWIFE--- v w w mm R O oNflH 5 D 6 W? w m; H w. m m m w M b M T n 7% 1 1mm a 9 L m H a I 1 m m Em 5 MW WM M m mm w w l|||| 0 en RP E 0 0. Fa A Fwe 0 7 0 w w 1 1 1 m mm M P a P a P 5 u UP P 0 0/ M/ pm m m FRO/VRECE/VEI? Feb. 28, 1950 D. D. GRlEG MULTIPLEX ELECTRICAL PULSECOMMUNICATION SYSTEM Filed Sept. 29, 1945 15 Sheets-Sheet 6 A TTOIPNE'YD. D. GRIEG Feb. 28, 1950 MULTIPLEX ELECTRICAL PULSE COMMUNICATIONSYSTEM l3 Sheets-Sheet 7 Filed Sept. 29, 1945 a m m w 6 a 0 M E I A 4| Mmy HI I w 4| k I m m 1 I k H I J I I 5 I 5 24 1 7 H 4I m1 my I I 4| P I9 7| m V my I V I 0 0 w L L H L Q) 7M, m w w M w w m m w m M W M M M M 5w a a m M H m c 14 TTOR/VEY D. D. GRIEG MULTIPLEX ELECTRICAL PULSECOMMUNICATION SYSTEM Feb. 28, 1950/ 13 Sheets-Sheet 8 Filed Sept. 29,1945 70 TP/M/SM/TTEI? 1 6 m. 9 M 1 M m f M X F n MM 8 a a M F R R k n@35 0? M 21 1 Z M M; a L 0 u W2 MM Z, 7 3 M M Z Z m w 1 M M M I M M M 1V V V M H n e 7 7 m ,0 L Q m x L 1+ 7 H M M 9 a 4 M 1 M M M M M I G M /MM 6 n M m M M 5 Mn} M f E I lllllllll 55" Tv w a WM I 71 E n H v 0 5 9 M2M2 I: w 1 5 E w n m .v 1 M Q m mf 2 M 7 ME" my 2 s U 4 A.HH|||1||| MMMM v 8 H PM 5 M E. El. M m m i M M i M W E T 7m R 2 ii F P 2 g f I M M MMM 7 M M n w a w Z M U W Y punt; I; M E g Fm M W M w w w a m MW m ,r/ EF n D Z za W6 WVWIIL I I I I I l INVENTOR. flOA/HLD 0 G/F/E'G BYATTORNEY D. D; GRIEG MULTIPLEX ELECTRICAL PULSE COMMUNICATION SYSTEMFeb. 28, 1950 Filed Sept. 29, p45

n$o w W M 2 M R M C 2 ii"?! f k v R t E n mm W m mm x w? M H U 6 0 5 40a w wt} 0 in 5 1: "in y a N4: H. mm am u a W" $0 WW Mm m 0 z an; um 6 cm 9 E a MP5, I W: {L i1| 2 V m P. YE m 2 M A 6 r AK 6 E m n f w i a 5 02 0 d e 8 G M" A M L A L I. fl m M M M N m w m m w m a s a a J T/ME 'INVENTOR. 001mm 0. 0mm

ATTGRA/EY .Feb. 28, 1950 D. D. GRIEG 2,498,678

MULTIPLEX ELECTRICAL PULSE COMMUNICATION SYSTEM Filed Sept. 29, 1945GROUP l3 Sheets-Sheet l2 n n ,275 I I I 274 TIME INVENTOR- DON/7L0 0.6/9/56 ATYU/PNE'Y Patented Feb. 28, 1950 MULTIPLEX ELECTRICAL PULSECOMMU- NICATION SYSTEM Donald D. Grieg, Forest Hills, N. Y.,as'si'gnorto' Federal Telephone and'Radio Corporation, New York, N. Y.,a corporation of Delaware Application. September 29, 1945, Serial No.619,405

16 Claims. I

This invention relates to multichannel communication systems. Moreparticularly it'deals with the method and means for producing a complexpulse modulated wave wherein each pulse carries more than one signalchannel,

It is an object of this invention to produce a complex pulse wavecarrying a train of pulses wherein each pulse carries more than onesignal in a novel and eliective manner.

Another object is to transmit and receive such a complex pulse wave.

Another object is to multiplex the pulses of such a pulse wavevertically by stacking two or more signals in a step shaped pulse.

Another object is to horizontally multiplex such step shaped pulses byinterleaving trains of them.

Another object is to demodulate such multiplexed pulse waves.

Another object is to width modulate different portions of each pulse;

Another object is to time modulate different portions of each pulse.

Another object is to time modulate the distance between two successivepulses of the same pulse train in accordance with a signal.

Another object is to time modulate both the leading and trailing edgesof each pulse according to different signals.

Another object is to avoid cross-talk between two adjacent signalchannels.

Another object i'sto provide means for carrying out the above objects.

Still other objects of this invention will appear from time to time inthe description which follows.

Generally speaking, the means for producing the complex pulse wave ofthis invention comprises: (1) a plurality of sources of signal energy,such as code signals, audio signals, or the'like; (2 means to produce aplurality of pulse trains respectively signal modulated with the energyfrom said sources; and (3) means to multiplex these pulse trainsvertically, and then alsohorizontally, to produce the desired complexwave.

The means to produce thes pulse trains comprises a base wave source orgenerator such as for producing a series of constant frequency pulses, asine wave, a saw-tooth wave, or other wave from which pulses may beproduced possessing a sloping leading and/or trailing edge. This wave isthen signal modulated, delayed, clipped, differentiated, or the like, toproduce separate trains of tim modulated pulses one corresponding toeach of the signals to be transmitted. The base wave may be signalmodulated to produce: a train of pulses each one of which is widthmodulated, or a train of pulses which are time modulated, or a train ofpulses in which either the leading edge or the trailing edge orbothedges of each pulse are time modulated.

The resulting pulse't'rains are then mixed to produce a complex pulsewave wherein the'signal pulses of at least two trains are verticallymultiplexed by superposing one upon the other'to prodime a step'shapedpulse. Trains of these step shaped pulses may further be horizontallymultiple'xe'd by interleaving them. One step shaped pulse may containmore than one type of modulatedsignalenergy, for example, the lowersteps maybe width modulatedand the'upper steps may be timemodulated. Inorder to facilitate in the demodulation of trains of horizontallymultiplexed pulses, a synchronizing pulse ofdiilerent shape, amplitude,and/0r width, may be'interleaved between the pulses at regularintervals.

The complex waves thus produced may be transmitted at ultra highfrequency by radio or by wire; The transmitted wave is received anddemodulated first, by dividing the complex wave of the separatetrainsof'pulses one correspondingtoea'ch' signal channel and, then,demodulating the resulting separate pulse trains. The separation meansmay comprise blocking-means if thecomplex wave is horizontallymultiplexed, and"clipping means for separating the different pulsesignals on each step of the step shaped pulses. When the leading edge ofa separated pulse is'modulated according to a different signal than thetrailing edge of that pulse, these two edges may be separated bydifferentiating the clipped pulse train to segregate the leading edgechannel, then phase inverting the resulting differentiated pulse wave tosegregate the trailing edge channel.

These and other objects and features of this invention will become moreapparent upon consideration of the following detailed descriptions of afew illustrative embodiments of the invention to be read in connectionwith the accompanying'drawings in which:

Fig. l is a schematic wiring diagram partially inblock of one'embodimentof this invention for producing a vertically multiplexed complex stepshaped'pulse wave;

Fig. 2 is a graph of the Wave forms useful in explaining the operationof the system shown in Fig. 1

Fig. 3 isagraph ofa group of wave forms which may be produced inaccordance with a variation of operation of the system shown in Fig. 1;

Fig. 4 is a schematic wiring diagram partially in block of ademodulating system for the complex wave produced in the system of Fig.1;

Fig. 5 is a graph of the wave forms useful in explaining the operationof the system shown in Fig. 4;

Fig. 6 is a schematic wiring diagram partially in block of anotherembodiment of this invention for producing a vertically modulatedcomplex step shaped pulse wave;

Fig. 7 is a graph of the wave forms useful in explaining the operationof the system shown in Fig. 6;

Fig. 8 is a schematic wiring diagram mostly in block of a system fordemodulating the complex wave formed in the system of Fig. 6;

Fig. 9 is a graph of the wave forms useful in explaining the operationof the system shown in Fig. 8;

Fig. 10 is a schematic wiring diagram partially in block of anotherembodiment of this invention for producing a vertically multiplexedcomplex step shaped pulse wave; I

Fig. 11 is a graph of the wave forms useful in explaining the operationof the system shown in Fig. 10;

Fig. 12 is a schematic wiring diagram partially in block of anothersystem for producing a vertically multiplex complex step shaped pulsewave similar to that shown in Fig. 10;

Fig. 13 is a graph of the wave forms useful in explaining the operationof the system of Fig. 12;

Fig. 14 is a schematic wiring diagram partially in block showing asystem for demodulating the: complex wave formed in the system shown inFig. 10 or Fig. 12;

Fig. 15 is a graph of the wave forms useful in explaining the operationof the system shown in Fig. 14;

Fig. 16 is a schematic block diagram of an embodiment for horizontallymultiplexing the vertically multiplexed signal pulses produced by any ofthe previously disclosed systems;

Fig. 17 is a graph of the wave forms useful in explaining the operationof the system of Fig. 16;

Fig. 18 is a schematic wiring diagram partially in block of a system forseparating and demodulating the vertically and horizontally multiplexedcomplex pulse wave produced in the system of Fig. 16;

Fig. 19 is a graph of wave forms useful in explaining the operation ofthe system shown in Fig. 18;

Fig. 20 is a schematic block wiring diagram of another type ofhorizontal multiplexing system wherein a synchronizing pulse isgenerated to separate each group of different step shaped pulses;

' Fig. 21 is a graph of wave forms useful in explaining the operation ofthe system of Fig. 20; and

Fig. 22 is a schematic block wiring diagram of a system for demodulatingthe horizontally multiplexed pulse wave produced in the system of Fig.20.

This specification is divided into the following chapters:

Chapter I-A is illustrated by Figs. l-5 which discloses a system forproducing and demodulating a step shaped pulse wave in which thehorizontal width of the pulse at each step is modulated according to adifferent signal; and in which a time modulated pulse is superimposedupon the top of each step shaped pulse.

Chapter I-B illustrated by Figs. 6-9, discloses a system for producingand demodulating a complex step shaped pulse wave in which the width ofeach step of the pulses is the same but the time distance between thecorresponding step on two adjacent pulses is varied according to a givensignal.

Chapter I-C illustrated by Figs. 10-15, discloses two systems forproducing and one system for demodulating a complex pulse wave in whicheach edge of each step of the pulses is modulated according to adifferent signal.

Chapter II-A illustrated by Figs. 16-19, discloses one embodiment of asystem for producing and separating horizontally multiplexed step shapedpulses produced according to the systems in the above figures.

Chapter II-B illustrated by Figs. 20-22, discloses another embodiment ofa system for producing and separating horizontally multiplexed stepshaped pulses incorporating a synchronizing pulse at regular intervalsbetween the step shaped pulses of a complex pulse wave.

Chapter I deals only with complex waves having vertically multiplexedsignal channels and Chapter II deals with complex waves having bothvertically and horizontally multiplexed signal channels.

Chapter I-A Referring to Figs. 1 and 2, the base wave generator I mayproduce the wave 2 shown in Fig. 2 or the wave 3 shown in Fig. 3. Thiswave passes through lines 4 to modulator clippers 5, 6, l and 8 and mayalso pass to other modulator clippers, if desired. Coupled with eachmodulator clipper is a source of signal energy, namely signals a, b, cand 01 introduced through lines 9, If), i l and i2 respectively. Thecircuit of a modulator clipper may comprise a double diode l3 to produceconstant width clipping levels I l that vary from less to more positivepositions between limits l5 in accordance with the signal a connectedthrough transformer I6. The variable resistances l1 and 18 determine thewidth between the clipping levels I l. Since the clipping levels It varyvertically along the sloping portion of the wave 2, the edges of thepulses of clipped pulse train I9 are horizontally or width modulatedwithin the limits 20. The train M! then passes through line 2| to themixer 22. Similarly, in-modulator clippers 6 and l the signals 1) and cproduce the pulse trains 23 and 24 which also pass into the mixer 22through lines 25 and 26, respectively.

As distinguished from signals a, b and c, signal (2 may be timemodulated. This may be carried out by differentiating and clipping thepulse train 21 produced in the modulator clipper 8 and passing itthrough line 28 to the differentiator clipper 29. The differentiatorclipper 29 may comprise a differentiating circuit of condenser 30 andresistor 3! and a clipper tube 32 which may have its clipping voltageapplied through the resistor 3|. From the difierentiator is withdrawnpulse train 33 which is clipped along level 34 to remove only thepositive pulses 35. These pulses 35 are withdrawn from the plate of tube32 through the line 36, to the mixer 22. When the top width of pulse I9is very narrow, the pulses 35 may be retarded by a delay circuit 36a anamount is so as to more closely center the pulses 35 with respect to'thepulses Hi.

The mixer 22 may comprise a network of triodesriil, one for eachchannel, thus preventing feedback of energy irom'one channel to another.The plates of all the tubes 31 are connected together through line 38.to a suitable ultra high frequency transmitter. Line 38 carries thecomplex vertically multiplexed step shaped pulse wave 39 in which eachof the pulse trains I9, 23, 24, 35, are superimposed or stackedvertically to form the step pulses 48 with the time modulated pulses "35from pulse train 21 on the top of each step pulse 40. It is desirablethat the clipping operations .for channels a, b, c and (2 occur atspaced levels along the edge of the waves 2 or .3 so that the pulses ofdifferent trains will have different widths to permit stacking and sothat asuita'ble space is allowed'be'tween each of the level limits I5 toprevent crosstalk from one channel to another.

In Fig. 3 pulse trains 4|, 42, and 43 are produced 'to correspond tochannels a, b and c and to pulse trains I9, 23 and 24 of Fig. .2. Onlythe .leading edges of the .pulses of trains M, 42 and 43 are modulatedwithin the limits 44 because of the shape of the wave 3. The resultingcomplex wave 45 has step shaped pulses 46 corresponding to complex wave39 and pulses 40.

Referring to Figs. 4 and 5, the transmitted complex pulse wave 39 or '45is received over line 46 separately connected to channel clippers 41,48, 49 and 50 corresponding to the channels a, b, c and d respectively.The channel clipper may comprise a double diode 5i connected similarlyto the double diode I3, shown in Fig. 1 for clipping off pulse trains52, 53, 54 and 55 corresponding to pulse trains I9, 23, 24, and 35 ofchannels a, b, c and (1 respectively. By adjusting the values of theresistances 56 and 51, different steps of the step shaped pulses 40 or46 are selected. The resulting separated width modulated pulse trains52, 53 and 54 are then respectively passed through pulse widthdemodulator circuits 58, 59, and 60 from which signals a, b, and c arewithdrawn through lines BI, .62 and 63. The pulse width demodulator maybe of the type disclosed in my copending application, Serial No. 547,124

.filed July 29, 1944, now Patent No. 2,421,025,

granted May 28, 1947, comprising a pentode tube 64 for amplifying thecurrent in the pulses before it is passed into the oscillating timeconstant circuit 65 (of an inductance and capacitance) which is tuned toconvert the width modulated pulses into amplitude modulated pulses. Theunwanted portions of the waves produced by the oscillating circuit 65are damped in the damping tube 66 and the resulting wave portions arethen clipped in the clipping tube 61 so that only the first undulationof the wave produced from each pulse is passed through line 68 as pulsewave 69 into a low pass filter from which is withdrawn signal wave IIthrough line 6|. Pulse waves I2 and I3, from which are produced signalwaves I4 and I5 are withdrawn through lines 62 and 63, respectively andcorrespond to signals b and c.

The time spaced pulses 35 of the separated pulse train 55 may bedemodulated in the time demodulator I6, similar to that described in mycopending application, Ser. No. 459,959, filed September 28, 1942, nowPatent No. 2,416,306, granted January 27, 1948. This demodulatorcomprises mixing the pulse train 55 with a harmonic wave from source 11in the tube I8, and then passing the resulting mixed wave, whichpreferably is clipped by a suitable grid bias through a low pass filterI9, similar to that of 6 "I0, from which is withdrawn thesignal (1through line8ll.

Chapter I-B Referring now to Figs. Band 7 for the production of timemodulated .pulses of equal width there is :shown a sine wave generator81 for producing the-sine wave'02 which (1S coupled-through line '83 tocusper modulators '04, and 86 'to which are also coupled'signal energiesfrom signals a, b, and 0 through .lines 81, 88 3111(1789 respectively.The zcusper modulator may be similar to that described in my :jointcopending application, Ser. No. 455,898, filed August 24, .1942, now.Patent No. 2,434,936, granted January 27., 1-948, wherein the base sinewave and signal energywave comprise the ,primary of transformer 90. Fromthe secondary .are coupled :a :pair of equally biased triodes 9| torectify the sine wave 82 :and to produce wave 92 having cusps '93 timemodulated :in pairs toward and away from each other corresponding 'tothe :signal energy impressed on (the primary through line 8.1. Theresulting :cusp modulated wave is then clipped at the level of channelashown in Fig. '7 by the double clipper '94, similar to that shown at'41 in .Fig. 4, "to produce a pnlse train 940, which is withdrawnthrough line .95, to :mixer 96. Signals 'b and-caresimilarlyrmodulatedzon the cusp wave 92, but are clipped at izlifferentchannel ;levels 2) :and c as shown :in Fig. 7 by double clippers 9-1 and9-8, respectively, to produce pulse trains 99-and I00 :whichare passedto mixer96. Mixer '96 may be similar '-to mixer 2-2 shown in Fig. 1. Thevertically multiplexed complex wave from mixer 96 and withdrawn throughline I04 for transmission, is shown at I02 in Fig. 7 havingstepshapedpulses I03 producedrby superimposing thej'pulses-of trains 94,99 and I00.

The "vertically multiplexed complex pulse wave 408 may be demodulated inthe system shown in Figs. 8 and9 by passing from line I64 through aseriesof double-clippers I05, .106, I01, similar to the double clipper96 or 41 above mentioned, wherein-each step-0f the pulses of wave I03 isdivided into pulse trains I08, I09, ll-corresponding to channels a, b,and 0. These trains 408, I09, III] are then passed through-.differentiator clippers III, H2 and H3, respectively, .(sirnilar todifferentiator-clipper .29 shownin Fig. 1) from Whichare withdrawn onlythe positive ;pulses of trains H4, H5, =I.I6. These pulses-are then timedemodulatedin time demodulator circuits II], II 8 and H9, similar tothat shown at 16 in Fig. 4. In Fig. .9 is shown the harmonic wave I20from harmonic wavegenerator I21, upon which there issuperimposed thepositive pulses-of wave H4,

amplified in tube I22. After passing the resulting wave through the low,pass filter I23, the signalwave I24 is withdrawn through line I25.Similarlysignals'b and c are withdrawn through line I26 and 12'!respectively.

Chapter [-0 shown at 5 in Fig. 1, to produce a pulse train 7 I33, and adifierentiator clipper, similar, to that shown at 29 in Fig. 1 fromwhich is withdrawn a wave having positive pulses I34 corresponding onlyto the leading edge of the pulses in train I33. These pulses I34 arethen passed through line I35 into mixer I36.

To produce the pulses for signal I) the base sine wave I29 may be passedthrough line I31 into a suitable delay device such as phase shifter I38comprising a condenser I39 and resistance I40, from which is withdrawnthe delayed sine wave I4I shown in dotted lines in Fig. 11. Signal b isthen time modulated from wave I4I, similar to wave I29, in the pulsetime modulator I42 from which is withdrawn (through line I43) a seriesof positive pulses I44 and passed into the mixer I36. Mixer I36 maycomprise a pair of triodes connected similarly to those shown in mixer22 in Fig. 1. From mixer I36 is withdrawn the two channel pulse trainI45 which is passed into the trigger circuit I46 to produce pulse trainI41. This trigger circuit comprises two triodes I48, one of which firesto pass current in response to pulse I34 and continues to pass currentuntil pulse I44 cuts it out and causes the other tube to i fire andremain conductive until the next pulse I34 again fires the first tube.This circuit couples adjacent pairs of pulses I34 and I44, to producethe leading and trailing edges respectively of a new pulse I49 on pulsetrain I41.

Similarly, other phase shifters I50 and I5I delay the base sine wavefrom line I52 to produce delayed waves I53 and I54 which arecorrespondingly passed through pulse time modulators I55 and I56 toproduce trains of positive pulses I51 and I58 corresponding to signals 0and d. These pulses are then passed through lines I59 and I60 to themixer I6I to produce two channel pulse train I62 and thence to a triggercircuit I63 similar to I46 to produce the pulse train I64. The pulsetrains I41 and I64 are mixed in mixer I65 to produce the verticallymultiplexed complex pulse wave I66 which is withdrawn through line I61for transmission.

Another system is shown in Figs. 12 and 13 for producing a wave similarto wave I66 having both the leading edge and the trailing edge of eachstep of each pulse modulated according to a different signal. A pulsewave generator I68,

which produces a wave similar to that shown at I69 in Fig. 13, iscoupled respectively to two separate wave shapers: leading edge wavshaper I10 and trailing edge wave shaper I1I.

Wave shaper I10 comprises a triode I12 and a condenser I13 for invertingand producing pulses having a sloping leading edge I14 from the pulsesI15 of wave I69. The resulting wave I16 passes through line I11 toseparate mod lator-clippers I18, I19 and I80, similar to those shown inFig. l, where each of the pulses of wave I16 are clipped at difierentlevels corresponding to signals a, c and e to produce pulse trainssimilar to those shown in Fig. 3, and passed to the mixer I8I.

Wave shaper I1I comprises a suitable delay device I82 which may consistof a network of inductances and capacitances to assimilate atransmission line. The resulting delayed base wave is then passedthrough a phase inverter I83 comprising a triode I84 and connectingcircuits from which is withdrawn through line I86 an inverted anddelayed pulse wave I85. This pulse wave I85 is delayed sufficiently sothat the vertically trailing edge of the pulses on wave I16 are insynchronism and alignment with th vertical leading into a mixer 2I1.

edge of the pulses on wave I85. Wave I then passes through thedifferentiator clipper I81, similar to that shown at 29 in Fig. 1,wherein wave I88 is produced and the positive pulses thereof havingtrailing sloping edges I89 are clipped from the remainder of the wavealong line I90. Since the clipping tube in the differentiator clipperI81 inverts the wave I88 it is then passed through another phaseinverter I1 Ia similar to I83 to produce the positive pulses I89. Thesepositive pulses I89 are then passed through line I9I to another group ofmodulator clippers I92, I93, I94 similar to modulator clippers I18, I19,I80. Each one of the modulator clippers I92, I93, I94, are respectivelyconnected with signals 1), d and J from which are produced a series ofpulse modulated wave trains as from wave I16, which trains are alsopassed to mixer NH. The addition and combination of these pulse trainsin mixer I8I forms the complex step shaped pulse Wave I95 which ispassed through line I96 to a suitable transmitter. In combining thepulse trains from waves I16 and I88, there may be an instantaneousvertical pulse (not shown) corresponding with the edges I91 and I98 ofthe pulses of these two pulse waves. However, if such an instantaneouspulse is objectionable it may be removed by passing the wave I95 througha filter device (not shown).

A suitable system for demodulating complex wave I66 or I95 is shown inFigs. 14 and 15 wherein the received complex wave passes through lineI99 to respective channel clippers 200, 20I, 202, for separating thesteps of the step shaped pulses by clipping pulse trains for channels aand b, c and d, and e and f as shown in Fig. 15. The pulse train 203 ofchannels a and b is passed through diilerentiator 204 from which iswithdrawn pulse train wave 205. This train wave 205 is then passedthrough clipper 206 wherein the positive pulses of the Wave 205 arepassed to form pulse train 201 corresponding to signal channel a. Train201 is then demodulated in pulse time demodulator 208 from which iswithdrawn the signal a. This signal a corresponds to the leading edge ofthe top step pulse of complex pulse wave I95. train wave 205 fromdifferentiator 204 is also passed through the phase inverter 209 whichmay comprise a. triode 2 I0 from the plate of which is withdrawn pulsetrain Wave 2II. Wave 2 is then clipped in clipper 2I2 (similar to 206)to produce the pulse train 2I3 corresponding tosignal channel 1). Train2I3 is then demodulated in pulse time demodulator 2I4 from which isWithdrawn the signal 1) corresponding to the trailing edge of the topstep of the pulse of complex pulse wave I95. Similarly signals 0, d, eand f are separated from the complex wave I95 according to the circuitshown in Fig. 14.

Chapter II-A The vertically multiplexed step shaped pulses, produced bythe system above described, may also be horizontally multiplexedaccording to the following systems. In Figs. 16 and 17 is shown the basewave generator 2 I5 which is respectively connected to channel modulatorcircuits a, b and c of group I modulator circuit 2I6 and thence Thesemodulator circuits clip the base wave 2I8 into a series of pulse trainsH9, 220 and 22I, corresponding to signals a, b and c. The base wave 2I8is also passed through line 222 into a delay device 223 which may besimilar to that shown at I62, in Fig. 12, to pro- The differentiatedduce a, delayedbase wave 224 which is then, connected to. the. channel,modulator circuits d, e, and f of group II modulator circuits, 225 fromwhich are withdrawn. pulse trains 226, 221' and- 228respectively,,andpassed into mixer 2 H. The delayed wave 224 may then further be passedthrough line 229 to another delay-device similar to, 223? and, thence.to a group III modulator circuits (not shown) to produce more pulsetrains which are also connected with the mixer 2H. From the mixer 2l1'the vertically and horizontally multiplexed step shaped pulse wave 230is withdrawn through line 23.] to a suitable transmitter.

A system for separating the channels of a horizontally and Verticallymultiplexed pulse wave similar to complex wave 239 is shown in Figs. 18and 19. The complex wave 239' is passed from the receiver through line23!v to a blocking wave circuit 232 and also to the group selectors233", 234, etc., for the separation of the pulses of. group I, group II,etc. The blocking wave circuit 232- produces the blocking wave 235. fromthe complex wave 238 by first passing it through a high Q circuit 236comprising a triode 231 and a time constant circuit 238. This high Qcircuit produces a smooth sine wave 238 which has the same frequency ascomplex wave 238. The phase of this sine wave 239 is then adjusted incircuit 229 so that the beginning of each cycle thereof is insynchronism and alignment with the space 24! between the two successivestep shaped pulses 222 of wave 238. This variable sine wave phaser maycomprise a condenser 2 13 and a variable resistance 244. From the sinewave phaser the adjusted sine wave 23.9 is passed intov a double clipper245, which may comprise a double diode 246 similar to that shown in Fig.1, from which is withdrawn the rectangular shaped wave 291. This wave241 is then differentiated in the differentiator 298, comprisingcondenser 249, and resistance 269, to form the pulse wavev 25L Pulsewave 25l is passed into a tuned multivibrator circuit. 252 which maycomprise two triodes 253 and two variable time constant circuitsconsisting of variable resistor 254 and condenser 255 and variableresistor 2'56 and condenser 251'. Multivibrator circuit 252 is so timedthat it will produce: (1') pulses 258' on wave. 235, which pulsescorrespond in width to the distance between two successive spaces. 24!.of the complex pulse wave 239; and will also produce (2) spaces 259between the pulses 259 so that pulses 2.58 will have the same frequencyas the step shaped pulses of one group. The blocking wave 235 is thenpassed through line 268 into. group I, separator 265! which comprises atube 262 for mixing it with the complex pulse wave 23!), introducedthrough line 263. This tube 282 may also be biased so that the compositewave 264 (produced by mixing the wave 238 and 235) is clipped at thelevel 265 so that only the pulses of group I are withdrawn from theplate of tube 262 through line 25.6. The group I pulses then are passedto demodulator circuits 26'! provided with a series of channeldemodulators a, b and c from which the corresponding reproduced signalsa, b and c are withdrawn.

In order to separate the complex pulses of group II, the wave 235 fromline 268 is passed to the group II selector 234 which is provided with.a delay device 261 for delaying the pulses 258. so that they will be inalignment with the pulses of group II on the complex wave 239. Thisdelayed blocking wave is then passed into a mixer 10 clipper 268,similar try-26!, and mixed with the complex wave. 238 from which iswithdrawn a pulse wave comprising the pulses of, group II and which ispassed through line 269' to the group II demodulator circuits 219 fordemodulating signalsd', e and J;

The pulses ofgroup III may be similarly separated by a group selector(not shown but similar to 234) connected with lines 2H and 212.Theseparated signal channels on each pulse group mayv be separated,and/or demodulated by any one or the systems previously described. Forexample, a pulse train- 21-3-is shown corresponding to channel; a'ofgroupI in Fig. 19, and this channel' may be differentiated and clippedto form pulse train- 214 fortime demodulation of the positive pulses 215according to a circuit previously described.

If'desired; thestep shaped pulses ofwave 232. may be Clipped to separatethe steps prior to blocking for separating the pulse trains of eachsignal channel.

Chapter 11-3 If desired similar groups of step shaped pulses in ahorizontal multiplexed complex Wave may be separated by synchronizingpulses.

A system for producing such synchronizing pulses is shown in Figs. 20and 21 wherein the base wave generator 216; producing the wave 211 isfirst passed; through a double clipper 218, similar to 5' shown in Fig.1, wherein the top of the wave 211 is clipped at levels 219 to produce apulse wave- 280 having synchronizing pulses 28L This Wave then passesthrough line 282 into the mixer 28.3. The base wave 211 is alsoconnected wah delay devices 2'84, 285, etc., for producing delayedw'a-ves 286, 281', etc., respectively. Delayed base wave 286- then maybe passed throughgroup I channel modulator circuits .288 such as thosedescribed in Chapter II-A above, for producing pulse trainscorresponding to channels of signals a, b, c and d as shown. Theseresulting pulse trains are separately passed through lines 289 intomixer 283. Similarly. signals e, f, g and h are modulated on furtherdelayed base wave 281 in the group II modulator circuits 299, whereinanother group of pulse trains are produced and passed through lines 29linto the mixer 283. From mixer 283 is withdrawn through line 292 acomplex pulse wave 293 having synchronizing pulses 28! between eachsimilar group of step shaped pulses 294.

The wave 293 may be separated and demodulated in a circuit similar tothat shown in Fig. 22.

' The incoming wave is passed through line 295 andthence into a, pulsewidth selector 296, similar to. the pulse width. demodulator shown inFig. i and having tube 64', time constant circuit 65, damping tube 66,threshold clipping tube 61, and the, circuits shown therewith. Thispulse width selector separates the synchronizing pulses 28! from. theother wider pulses 294 of the wave 293 thereby again, producing a pulsewave similar to 288, shown in Fig. 21. This synchronizing pulse wavesimilar to, 2.80 is passed through line 291 into a multivibrator 298,similar to that shown in 2.52 in Fig. 18, from which is produced ablocking wave. similar to 235,. shown in Fig. 19. This blocking wave isthen coupled to the group I selector 299 similar to group I selector 233in Fig. 18, and thence, t group I demodulator circ its 3.00, from whichare withdrawn signals a, b, c. and d, Group. II pulses, are, separatedin gro p. II selector sill, similar o. groupv II, 234 and gases- 11 7having a delay device, and from thence they are demodulated in the groupII demodulator circuits 302 from which are withdrawn signals e, ,f, gand h, as described in Chapter II-A above. The other groups aresimilarly separated in channel group selectors (not shown) connected tolines 303 and 304 of the received complex pulse wave and of the blockingwave respectively.

Although only six separate signals are shown modulated on a single stepshaped pulse, this is by no means a limitation on the number which maybe sent. More steps may be provided if the base wave is of a sufficientamplitude and frequency so that the time modulation of one pulse channelwill not overlap that of another pulse channel. The horizontalmultiplexing of such step shaped pulses may include ten or more in eachrepeated group of diiferent pulse trains provided the frequency of thecarrier for the wave is sufliciently high.

While the principles of the invention have been described in connectionwith several specific embodiments, it is to be clearly understood thatthe above descriptions are made only by way of example and not aslimitations on the scope of the invention as defined in the objects andthe accompanying claims.

I claim:

. modulate at least another of said signals on an- 1. In a multichannelsystem, means to produce a pulse having vertically disposed portions ofdifferent widths and means to modulate the width of each such portionwithin given limits according to the instantaneous value of a signal.

2. In a multichannel system, means to produce a pulse having verticallydisposed portions of different widths and means to time modulate eachsuch portions within given limits according to the instantaneous valueof a signal,

3. In a multichannel system, means to produce a pulse having Verticallydisposed portions of difierent widths and means to time modulate theedge of each such portion within given limits according to theinstantaneous value of a signal.

4. A system for producing a complex pulse wave carrying a plurality ofchannels of signal energy, comprising means for producing a plurality ofpulse trains respectively signal modulated in a time characteristic withthe energy from said signal sources, and means to superimpose the pulsesof :at least two of said pulse trains to produce said complex wave, thepulses of each separate superimposed train having difierent basicwidths, said means for producing the pulse trains including means totime modulate the pulses thereof according to the instantaneous valuesof the corresponding signal energy.

5. A system for producing a complex pulse wave carrying a plurality ofchannels of signal energy, comprising means for producing a plurality ofpulse trains respectively signal modulated in a time characteristic withthe energy from said signal sources, and means to superimpose the pulsesof at least two of said pulse trains to produce said complex wave, thepulses of each separate superimposed train having different basicwidths, said means for modulating the pulse trains including means towidth modulate the pulses thereof according to the instantaneous valuesof the corresponding signal energy.

6. A system for producing a complex pulse wave carrying a plurality ofchannels of signal energy, comprising means for producing a plurality ofpulse trains respectively signal modulated in a time characteristic withthe energy from said signal sources, and means to superimpose the otherof said pulse trains according to the instantaneous values of thecorresponding signal energy. I

'7. A system for producing a complex pulse wave carrying a plurality ofchannels of signal energy, comprising: means to produce a base wave, aplurality of sources of signal energy, means controlled by said basewave to produce a plurality of pulse trains respectively signalmodulated with the energy from said signal sources, and means tosuperimpose the pulses of at least two of said pulse trains to producesaid complex wave, the pulses of each separate superimposed train havingdifferent basic widths.

8. A system for producing a step shaped pulse on a pulse wave whereineach pulse carries at least two channels of signal energy comprising: atleast two sources of signal energy, means to produce a base wave havinga sloping edge, means for clipping said base wave along said slopingedge at various levels corresponding to the energy from said signalsources to produce at least two pulse trains corresponding to saidsignal sources, the pulses of each train having different basic widthsand having the same frequency, and means to superimpose the pulses of atleast two of said pulse trains to produce step shaped pulses on said.pulse wave.

9. A system for producing a step shaped pulse on a pulse wave whereineach pulse carries at least two channels of signal energy comprising: atleast two sources of signal energy, means to produce a sine base wave,means to cusp modulate said base wave corresponding to energy from saidsignal sources, means to clip said modulated cusp waves at difierentamplitude levels for different channels to produce pulse trainsrespectively signal modulated with the energy from said signal sources,the pulses of at least two separate trains having different basic widthsand having the same frequency and means to superimpose at least two ofsaid pulse trains having the same frequency to produce said step shapedpulse on said ulse wave.

10. A multichannel system for producing a complex pulse wave wherein atleast two signal are vertically multiplexed on a single pulse and thesepulses are horizontally multiplexed with other vertically multiplexedpulses comprising: a plurality of sources of signal energy, a base wavesource, means to delay said base Wave to produce a delayed waveout-of-phase with the original base wave, separate means controlled bysaid base wave and said delayed wave to each produce a plurality ofpulse trains respectively signal modulated with energy from a separateone of said signal sources, the pulse trains produced from said delayedbase wave having a frequency outof-phase with the pulse trains producedfrom the original base wave, means for superimposing at least two ofsaid pulse trains produced from said base wave, means for superimposingat least two of said pulse trains produced from said delayed wave, andmeans for interleaving the superimposed pulses to produce said complexwave.

complex pulse wave wherein at least two signals are verticallymultiplexed on a single pulse and these pulses are horizontallymultiplexed with other vertically multiplexed pulses comprising: aplurality of sources of signal energy, a base wave source, means toproduce a synchronizing pulse from said base wave, means to delay saidbase wave to produce at least two delayed base waves out-of-phase witheach other and said original base wave, means controlled by each of saiddelayed base waves to produce a plurality of pulse trains eachrespectively signal modulated with energy from a separate one of saidsignal sources, the pulses of each train produced from a given one ofsaid delayed base waves having the same frequency and being out-of-phasewith the pulses of the pulse trains produced from the other delayed basewaves, means for superimposing at least two of the trains produced fromsaid given delayed base wave, and means for superimposing at least twoof the trains produced from said other delayed base wave, and means tomix said synchronizing pulses and said pulse trains to produce saidsuperimposed complex wave.

12. In a multichannel communication system wherein a complex pulse wavehaving at least two signals vertically multiplexed on each pulse thereofand wherein said pulses are horizontally multiplexed, a system fordemodulating said complex pulse wave comprising: means for producing ablocking wave from said complex wave, means employing the blocking wavefor separating the horizontally multiplexed pulses, means for separatingthe vertically multiplexed pulses to produce a plurality of pulse trainscorresponding to each signal modulated on said complex wave, andseparate means for demodulating said separate pulse trains to reproducesaid signals.

13. In a multichannel communication system having at least two signalsvertically multiplexed on each pulse thereof and wherein said pulses arehorizontally multiplexed and wherein similar groups of horizontallymultiplexed pulses are separated by synchronizing pulses, a system forseparating said complexwaves comprising: means for producing a blockingwave from said synchronizing pulses, means for employing said blockingwave for separating the horizontally multiplexed pulses, and means forseparating the vertically multiplexed pulses to produce a plurality ofpulse trains corresponding to each of said signals on said complex wave.

14. In a multichannel communication system wherein a complex pulse wavehaving at least two signals vertically multiplexed on each pulse thereofand wherein said pulses are horizontally multiplexed and wherein similargroups of horizontally multiplexed pulses are separated by synchronizingpulses, a system for demodulating said complex wave comprising: meansfor producing a blocking wave from said synchronizing pulses, means foremploying said blocking wave for separating the horizontally multiplexedpulses, means forseparating the vertically multiplexed pulses to producea plurality of pulse trains corresponding to each of said signals onsaid complex wave, and means to demodulate each of said pulse trains toreproduce said signals.

15. A multichannel communication system comprising: a base wavegenerator to produce a base wave having a sloping edge, at least twosignal sources, at least two means for clipping said base wave alongsaid sloping edge at various levels corresponding to the energy fromsaid signal sources within a given range, difierent level rangescorresponding to different signal channels, to produce trains of timemodulated pulses corresponding to each of said channels, means tosuperimpose at least two of said trains of pulses to form a singlecomplex wave, a transmitter for transmitting said complex wave, areceiver for receiving said transmitted complex wave, means to separatesaid complex wave into each train of each said signal channel, andseparate means to demodulate each said train into its correspondingsignal.

16. A method for producing a step shaped pulse on a pulse wave forcarrying a plurality of channels of signal energy comprising: producinga plurality of pulse trains respectively signal modulated with theenergy from said signal sources, said pulse trains having pulses ofdifferent basic widths and at least two of said trains having the samefrequency, and superimposing the pulses of at least two pulse trainshaving the same frequency to produce the step shaped pulse on saidcomplex wave.

DONALD D. GRIEG.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,199,634 Koch May '7, 19402,266,194 Guanella Dec. 16, 1941 2,311,021 Blumlein Feb. 16, 19432,401,384 Young June 4, 1946 2,406,790 Beatty Sept. 3, 1946

